Setting electric projectile fuses



Feb. l0, 1931. v H RUHLEMANN l 1,791,606

SETTING 4ELECTRIC PROJECTILE FUSES Filed April 16, 1928 ATI-n RN EY Patented Feb. 10, 1931 HERBERT RHLIMANN, OF' SOMMERDA,

GERMANY, ASSIGNOR T RHEINISCHE HETALLWAABEN- 'UND MASCHINENFABRIK, OF DUSSELDORF-DERENDORF, GER- IIANY SETTING ELECTRIC PROJECTILE FUSES Application led April 16, 1928, Serial N0.`

My invention relates to a method of setting electric projectile time fuses, in which the discharge of electric condensersis used to ignite the composition.

It has already been proposed to set electric fuses of this type by varyin the conditions of the discharging current o the condenser, which is loaded up always to aequal voltage, to which end anl adjustable high ohmic resistance is arranged in the discharging circuit, that includes the igniting means, of the condenseigso that according to the adjusted resistance amount the condenser is discharged more quickly or slowly through the ignitmg means, whereby an earlier or later ignition moment is obtained. l

According to my invention, the setting of diierent ignition moments is obtained by varying the loadin conditions of the condenser, that means, y ditferently measuring the loading voltage supplied to the condenser. By increasing this voltage amore rapid discharge of the condenser and therewith an earlier ignition moment is obtained, while a reduction of the loading voltage results in a slower discharge and therewith a later igniI tion moment. v j

To carry out this newmethod, a voltage `transformer is inserted in the circuit, that feeds the condenser of the fuse and is connected to a source of current,l which in a known manner is either arranged in theV pro'- jectile or separately therefrom. Furthermore, if a generator is used as source of current, according to the invention the generator itself is enabled to produce different voltages, by appl ing thereto regulating devices of known esign. So,e. g. when the source of current, united with the rojectile, consists of a permanent magnet s iftably arranged in an induction coil, either the relative speed of the shift of the magnet in the coil is made adjustable by means of a brake, or the number of windings of the induction coil is made adjustable, Vwhereby in both cases the voltage of the current generated is varied.

In combination with the measure of loading up the condenser of the fuse from a source of current that is se arate from the projectile, the setting metho of my invention is of a 270,465, and in Germany April 28, 1927.

particular advantage to obtain a very simple construction of the fuse and a very simple manner of setting it. In spite of this the fuse itself comprises only a condenser and a high ohmic resistance or a combination of several condensers as power accumulator, and the igniting means, that may consist simply of a spark or bridge ignitor, while no adjustable setting mechanisms need to be provided on the fuse itself or on the projectile. The setting of the ignition moments is eiected on the fuse loading apparatus which is separate from the projectile by suitably tuning the loading voltage, while the setting of the fuses takes place automatically in and by loading their condensers. Furthermore, when the contacts of the loading apparatus are arranged on the gun itself, that means either in the gun barrel ror closure, so that the loading and therewith the setting of the fuse takes place after the introduction of the projectile in the gun barrel shortly before or immediately in firing the projectile by actuating the tiring mechanism, the setting-to equal bursting moments of a series of projectiles to be fired succes;- `s1vely does not re u1re any speclal tlme-consuming measure. he firing speed of the gun ting of the fuses to a new ignition moment can 'be performed in a simple manner, even when the projectile is already in firing position in the gun barrel.

In order to allow of my new method to be Iis thus considerably increased and a re-setmore easily understood, the wiring diagrams of diiferent embodiments of fuses serving to carry out my setting method are illustrated in Figures 1, 2 and 4 of the drawing, that accompanies and forms part of this specification, while Figure 3 'shows the time-voltage curves of the condensers of a fuse designed according to FigureQ, with different loading voltages. i

In all the embodiments illustrated the fuses are loaded from a source of current, as shown in Fig. 1 by K having a variable resistance K1 which is separate from the project-ile and is adapted to deliver a voltage of an amount to be adjusted at will Within two limits. The fuse illustrated in Figure 1 is iitted with a condenser a serving as electric power accumulator, the two armatures al and a2 of which are interconnected through a high ohmic resistance h and an igniting means c. rEhe iatter is formed by an incandescent bridge igniter having a heating wire embedded in an igniting composition, the latter being heated by the wire up to ignition temperature when the current is ilowing therethrough. @n the outer surface of the projectile shell are provided two contact pieces as' and a4 which are insulated from the projectiie wail and may be connected to the poles di and d2, in a receptacle 1, of a source of current K. T he contact pieces a3 and a, suitably extended annularly round the shell and are conductively connected to the two armatures al and a2 of the condenser. The switch m closes when the projectile is fired so that the current from the condenser will flow through the igniting means c.

According to whether the condenser a has been ioaded with a current of higher or lower voltage, a current of higher or lower strength iiows through the igniting means c and its heating wire is heated up to the igniting temperature after a shorter or longer lapse of time. The highohmic resistance serves in principle to extend the discharge of the condenser on a certain period of time. bis this resistance is constant. according to Joules iaw the heat produced in the time unit in the heating wire oi' the gniting means is proportional to the square of the loading voltage introduced in the condenser a.

in the embodiment illustrated in Figure 1 a current begins to flow from condenser a through the igniting means c at once after loading the condenser a and disconnecting its contact pieces as and a, from the wires d1 and Z2 leading to the source of current.

Therefore, the projectile must be fired constrainedly lin ldependence on the loading of the condenser, and the loading itself must thus be edected in the gun barrel shortly before or when ythe projectile is fired.

n'order to load the -fuse by means of a' special apparatus arranged at a distance from the gun, according to an arrangement not showna contact device is inserted in the discharging circuit of the condenser a, which contact device is normally open and is designed as to be closed automatically by the action of inertia only when the projectile is red.

With the hereinbefore described fuse according to Figure l merely an incandescent wire bridge igniter can be used. Besides, due to the capacity of the condenser being not high, very distant ignition moments cannot be obtained, as in these cases the radiation of heat from the composition has a too great noxious influence, so that the temperature of the heating wire does not reach at all the degree re uired for the ignition.

These awbacks are obviated by the menace designed according to the'wiring diagr illustrated in Figure 2. rThis fuse contains two condensers e and f which are loaded u to equal voltage. The similar poles e1 and 1 of these two condensers are interconnected through a spark gap g and an igniting means h formed by a spark or wire bridge igniter. A high ohmic resistance z' is further connected in parallel to the condenser e.

rEhe spark gap g inserted in the circuit possesses a practically infinite resistance as to currents of a voltage lower than its sparking voltage, that means, only with a voltage of such as amount, that the gap is bridged under spark formation, a current ows through the spark gap and therewith through theigniting means. instead of the spark gap g another electric time lagrelay of similar action may be connected in series with the igniting means, 4so e. g. a glowing zone the electrodes of which are lodged in vacuo or in a gas-iilled space.

After loading the condensers e and f and disconnecting their contact pieces from the poles of the source of' current, the one condenser e discharges throu h the resistance A voltage grows thereby between the armatures el and f1 of the two condensers, which voltage after having reached a determined amount produces a spark over ap g. By the current flow thereby provoked through the igniting means 71, the composition of the latter is ignited, whereby further the ignition of the bursting charge of the projectile is edected in known manner. The spark gap g inserted before the igniting means k serves so to say as an automatic switch, which is bridged only upon an exactly determined voltage arising between the armatures e1 and f1 of the two condensers and, by previously acting as electric relay,it prevents any How of current throu h'the igniting means 7L and a discharge of tie condenser f. When the igniting means il, is formed by a spark igniter,

that possessesa practically infinite resistance' below the igniting voltage, the spark gap g mag be dispensed with.

yccording to the higher or lower voltage the condensers e and f are loaded up to, the one condenser e discharges through the constant resistance z' more quickly or more slowl and the voltage required to form the spar at g and to provoke a current flow through .the igniting means grows up between the between the two condensers is reached after the time t1, with the lower loading voltage E2 after the longer time t2 and so on. With a low loading voltage the discharge of the one condenser e through the high ohmic resistance z' does not take place so quickly. Hence, by raising the loading voltage, earlier ignition moments and by lowering the voltage later ones can be set and obtained. The ignition of the composition takes place immediately at the instant the current starts Howing through the igniting means 7L, the instant a', spark springs over at the gap dg; f' In the embodiment illustrate in Figure 4, the wiring diagram of which corresponds to that shown in Figure 2, the high ohmic resstance c', through which condenser e discharges, is designed as a regulating resistance.

This resistance c' can at first be made adjustable only within narrow limits and serves in this condition to adjust the fuse in manufacturing it. Thereupon, when the fuse is tested after assemblage, the resistance z' is so set, that, with a determined loading voltage the sparking voltage of the spark gap g is reached after an exactly determined la se of time. This measure allows of certain 1naccuracies that happen to arise in the manufacture, of the condensers, the spark ap etc. to be compensated for. Variations o the igniting means are of no influence on the ignition-moment, when the described connection is employed.

However, the resistance i can be made adjustable also within wider limits. In this case it is of advantage to lodge it in a rotatable ring like the composition rings used in time fuses.

In combination with a source of current that is capable to deliver a current of a voltage adjustable at will, an igniting device is thus obtained, which allows of dlerent ig- -niting moments to be set either by the mere different determination of the loading voltage for the condensers, or merely by determined variation of the discharge time of the one condenser e, or by simultaneously varying both the said loading voltage for the condensers e and f and the discharge time of condenser e.

What I claim, is

An electric time fuse system comprising an electric igniting means; at least one condenser adapted to store the ignition current; and an external source o' current having means to give up currents of different strengths for charging said condenser.

'In testimony whereof'I have aiixed my signature.

HERBERT RHLEMANN. 

